Wound repair after fractionated external beam radiation therapy and concomitant hyperthermia in an experimental rat model

Background. Fractionated radiation therapy (RT) with adjuvant hyperthermia (HT) is being used in the treatment of cancer with noted clinical success. However, little information regarding wound repair in tissues receiving this combination therapy is available for comparison of surgical risk. Consequently, this study was undertaken to assess the effects of this combined therapy on wound healing by quantitatively evaluating wound repair using tensile strength measurements. Methods. Four treatment cohorts were designated: sham control, RT alone (600 cGy/d for 4 days), HT alone (water bath at 41.8°C, subcutaneous temperature of 41.0±0.5°CCfor 60 minutes on days 1 and 4), and combined RT and HT. At 1 week after treatment, surgical incisions of the dorsal flank were made. Tensile strength measurements of wounds were obtained at 14 and 21 days after incision. Results. No significant differences were observed in the combined treatment arm (RT and HT) compared with the reduced wound breaking strength of RT alone. Statistically significant differences in tensile strength were seen when the control group or HT alone was compared with RT and HT or RT alone. Conclusions. Concomitant exposure to fractionated RT and specific HT conditions demonstrated no disproportionate alteration in wound tensile strength compared with radiation exposure alone in this animal model.